This application is based on and claims priority to Japanese Patent Application No. 2002-249249 filed on Aug. 28, 2002, the entire content of which is incorporated herein by reference.
The present invention relates to a valve timing control device which controls open and close timing of intake or exhaust valves of a combustion engine.
A conventional device of this kind is disclosed, for example, in Japanese Patent Laid-Open Publication No. 11-101107. This device is disposed between a crank shaft of a combustion engine and a cam shaft for opening and dosing intake or exhaust valves and controls open and close timing of intake or exhaust valves independently of the rotation of the crank shaft.
This device includes a timing sprocket which rotates with the crank shaft in a body, a housing which rotates with the timing sprocket in a body, a rotor which rotates relative to the housing and which operates the cam shaft and a vane which divides a fluid chamber formed between the rotor and the housing into an advance angle pressure chamber and a retard angle pressure chamber and which regulates the amount of the relative rotation between the rotor and the housing by the contact with end surfaces of a shoe portions formed on the housing. The vane is fitted into a vane groove which is formed on the rotor in the radial direction and rotates with the rotor in a body. Contacting portions are formed on the vane groove between a bottom portion and an opening end thereof and the rotational force is transmitted from the vane to the rotor through the contacting portions when the pressure difference is generated between the advance angle pressure chamber and the retard angle pressure chamber. A concave portion is formed on a radial inner end portion of the vane and a vane spring is disposed between the concave portion and the bottom portion the vane groove. The vane spring urges the vane outwardly in the radial direction so that a radial outer end of the vane slides on an inner wall of the fluid chamber.
In the above described device, however, a contacting area between the vane and a contacting portion of the vane groove is decreased by the concave portion of the valve. When the vane rotates with the rotor by the pressure difference between the advance angle pressure chamber and the retard angle pressure chamber, a driving force is applied to the vane due to the pressure difference and a load corresponding to the driving force is applied to the contacting portion of the vane groove. Further, when the vane regulates the relative rotation between the rotor and the housing by the contact with the end surfaces of the shoe portions, a reaction force is applied to the vane and a load corresponding to the reaction force is applied to the contacting portion of the vane groove. Therefore, in case that a radial length between the bottom portion of the vane groove and the radial inner end of the contacting portion is smaller than a radial length between the bottom portion of the vane groove and the concave portion, the surface pressure of the contacting portion increases and there is in danger that the contacting portions are worn.
It is, therefore, an object of the present invention to overcome the above drawback.
In order to achieve the foregoing object, the present invention provides a valve timing control device which includes a rotation member for opening and closing valves, a rotation transmitting member rotatably mounted on the rotation member, a fluid chamber defined between the rotation member and the rotation transmitting member, a vane fitted into a vane groove formed on the rotation member or the rotation transmitting member so as to divide the fluid chamber into a advance angle pressure chamber and a retard angle pressure chamber, the vane groove having contacting portions contacted with the vane and an elastic member dispose between the vane and the rotation member or the rotation transmitting member, wherein the radial length between the bottom portion of the vane groove and a bottom portion side end portion of the contacting portion is larger than a radial length been the bottom portion of the vane groove and an engaging portion of the vane engaged with the elastic member.